This invention relates to seals and more particularly relates to a novel and improved dynamic seal for pumps of the hydraulic sealing type and which are adaptable for use in pumping acids or slurries.
A. R. Wilfley & Sons, Inc. is the assignee of previously developed seals for centrifugal pumps which obviates the use of a packing gland or mechanical seal bearing directly against a rotating part but is capable of sealing against the leakage of liquid into the seal housing or reservoir when the pump is not in operation and has no hydraulic sealing capability. Conversely, when the pump is in operation, it will hydraulically seal against leakage of liquid from the expeller region into the seal housing or reservoir of the pump. For example, attention is directed to U.S. Pat. No. 5,667,356 to Whittier et al for ACID/SLURRY GOVERNOR ASSEMBLY FOR CENTRIFUGAL PUMPS.
Nevertheless, there is a continuing need for a dynamic seal of simplified construction which is conformable for use both with acids and slurries and which will prevent solids from settling into the cavity under the seal housing when the pump is not in operation, assists the expeller in solids evacuation from the expeller cavity and stationary seal faces, and effectively prevents the leakage of liquid from the expeller region into the seal housing of the pump when the pump is at rest. It is further desirable that the seal member have a variable spring constant according to its intended application and provided with outer sealing surfaces which can be composed of a material chemically compatible with the fluid to be sealed, flexible enough to withstand movement in adjusting to the width of the gap between the surfaces to be sealed and soft enough to form a liquid-tight seal with both confronting surfaces.
Other representative patents are U.S. Pat. No. 1,346,926 to Wilfley, U.S. Pat. No. 1,556,657 to Wilfley, U.S. Pat. No. 1,976,532 to Wilfley, U.S. Pat. No. 2,272,454 to Wilfley, U.S. Pat. No. 2,608,423 to Wilfley, U.S. Pat. No. 2,660,487 to Wilfley, U.S. Pat. No. 3,137,237 to Zagar et al, U.S. Pat. No. 3,472,169 to Dyke et al, U.S. Pat. No. 3,515,497 to Studebaker et al, U.S. Pat. No. 3,652,180 to Choquette et al and U.S. Pat. No. 4,915,579 to Whittier et al.